1. Field of the Invention
The invention relates to fluid bed reactors having granular material therein, which are used to biologically treat fluids, such as water, by aerobic or non-aerobic means, and in which the fluid to be treated flows from the bottom towards the top of the apparatus.
2. Description of Pertinent Information
It is well established that biological field bed reactors have numerous advantages over traditional reactors using free or immobilized cultures positioned on fixed beds. These advantages include: better contact between the water to be filtered and the bacterial mass, and retaining superior charge volumes by virtue of the very large specific surface area of the granular material.
Numerous reactors of this type have been developed. However, all of these prior art reactors have disadvantages which include difficulty in ensuring the introduction and homogeneous distribution of fluids into the granular material bed, as well as difficulty in disembedding, separating, and recycling the granular material.
Several reactors partially compensate for some of these disadvantages. For example, U.S. Pat. No. 4,202,774 and European Pat. No. 0,090,450 both describe a reactor using a plurality of devices for injecting the liquid to be treated through feeding orifices at several points along the base of the reactor. However, in these reactors there is the risk that these feeding orifices can become obstructed. In addition, there is no gas introduced into the reactor itself. Rather, the treating gas is generally mixed with the liquid to be treated before the introduction of the liquid into the reactor.
French Pat. No. 84.09235 to Applicant relates to a reactor using a fluid bed in which the water to be treated is introduced at a high speed into a layer of granular material, thereby transfering this water into a second layer of material which is rendered fluid. The granular material is washed and recycled in this second layer by means of a device attached to the exterior of the reactor.
However, known reactors such as those described above are not well suited for a three-phase mix comprising: the liquid to be treated; a treatment gas, such as air, oxygen, oxygen enriched air, or gas formed in the reactor such as methane; and the granular material. Thus, there is a need for a reactor that is well adapted to treat the three-phase mix as described above. There is also a need for a reactor that can produce a homogeneous distribution of fluids into the granular material bed, and that can easily and efficiently disembed, separate, and recycling the granular material.